ok so i was working on a 03 Dodge Dakota 3.9L 4x4. we replaced the rear axle assembly.

The axle that came off was a 8.25 ring/3.55 gears
we put in a 9.25 ring/3.92 gears

everything bolted right up, no mods needed.

we went to go start it, and the battery was somewhat dead (light was left on overnight)

we pushed it out of the garage so i could get my truck to jump it. It wanted to start, very close to catching but wouldnt go.

now the rear end is fine...we put a new speed sensor in (theres on 1 kind for both axles so that wasnt screwed up.) it shifts into all gears (with it off) and everything is fine. in neutral we could push it, so i know that the bigger axle is not the problem

we think its the battery having a dead cell. engine off, key on, the volts are reading very very low. then on jumper cables, its over halfway.

So with a rear end swap what could cause a no start? Do you think its the battery?


Also the new rear end came from a 03 Dakota...

 

Is it getting fuel and spark?

 

ummm... have you tried replacing the battery? if a battery is too low jumping it wont help it your best bet is to replace the battery and if you want to you can take the battery to autozone and have them test it and charge it first to see if that works. there is no reason why it shouldnt start due to a bigger axle u can start a car with no axle...

 

yes, theres fuel and spark,


the truck wants to start its very close, when cranking it sputters a little like its going to start but doesnt. when we take off jumper cables and try to start it on its own, it will crank about 4-5 times, and then nothing (like the battery is dead)


ZAKMAN, thats exacally what i was thinking. i had 2 96 maximas, and 1 got towed, got it back but the people who towed it left the key on (3 weeks.) tried jumping it and it did the same thing as the Dakota. put the brand new battery that was in the other maxima in it, and it fired right up.

Its not my truck, i did the job for a friends dad (old diff's LSD blew up) and hes getting the battery tomorrow, for i told him that could be the only thing, the only electrical thing we touched was the speed sensor, and that wouldnt make it not start..and the sensor we bought today, so its brand new. and was exacally like the old one